Electrical resistivity, strain and permeability of Pd-Ag membrane tubes

摘要

A Pd-Ag (silver 25 wt.%) permeator tube has been tested in order to measure the electrical resistivity, the strain, and the hydrogen permeability under different hydrogenation conditions in the temperature range 50-400 ℃. The permeator tube has been assembled into the membrane module in a finger-like configuration: pure hydrogen has been fed in the lumen side of the tube at a pressure of 100-400 kPa while the permeated hydrogen has been recovered in the shell side of the membrane via a nitrogen purge gas stream of 3.70 × 10~(-4) mol s~(-1) at atmospheric pressure.rnThe electrical resistivity increases with both the temperature and hydrogen pressure but a minimum of the resistivity is present at 100 ℃. The strain of the hydrogenated material increases with the hydrogen pressure and reduces with the temperature. Moreover, the relationship between the strain and the hydrogen content has been investigated and a power law for isotherms in the temperature range 50-400 ℃ has been found out. Values of hydrogen permeability of 1-2 × 10~(-8) mol m~(-1) s~(-1) Pa~(-0.5) have been measured in the temperature range 200-400 ℃: the results showed a modest influence of the hydrogen pressure while the dependence from the temperature follows the Arrhenius' law in agreement with literature.